Until today, machinery for circular knitwear is characterized by a continuous production through a program that establishes length and typology. A plurality of needles produces a number of shape stitches in such a way that, in a second step, the walls of the stocking are separated to enable closing of the walls of the stocking, which, until today, is carried out manually and mechanically.
More recently, autonomous mechanical accessories, to be applied by means of an interface to the circular machine, which is synergistically integrated and is inserted into the process, close the stitch. Such final step occurs, therefore on the textile members of the knitting machine, which remains engaged for a certain amount of time at the end of the knitting cycle of each product.
Such devices, therefore, though having evident automation advantages, have the disadvantage of breaking off the tubular production, by directly coupling to the rim of needles and by extending their normal manufacturing process to the closing of the toe. It is therefore evident how the production rate of the product is reduced with regard to a continuous tubular production cycle. Moreover, such devices are external to the machinery, and are always subjected during the installation, testing and in advanced production phases, to inevitable and continual checks and adjustments to allow for the perfect integration of the two different devices, that is, for the tubular production and the finishing/closing of the stocking.
In order to overcome the drawbacks of clamping arrangements of the toe in the circular machine, systems have been conceived and realized in which the completed tubular knit product is discharged from the needles and moved away from the knitting machine to be inserted in a sewing machine or darner. These systems are designed in order to engage the knit product with pick-up mechanical members, before this is discharged from the needles, so that it can be inserted in the sewing machine in a precise position, determined by the position in which the product has been taken from the needles. In fact, the seam must be carried out with a determined orientation as to the heel and to the toe formed by the fabric of the knit product.
For example, in US-A-2001/0017046, a system is described for the pick-up of tubular products produced by a circular knitting machine and for their transfer to a sewing machine. The system provides a series of hooks that are inserted into the needle cylinder of the circular machine and that, having reached a certain lifting position below the dial, expand to engage in a series of points of the tubular knit product. When the product is engaged, the hooks radially re-pull to allow the axial extraction of the product from the needle cylinder and therefore its transfer to the sewing machine.
U.S. Pat. No. 7,107,797 describes a different pick-up system of tubular knit products by a circular knitting machine and their transfer to a looping system. The pick-up is performed from above by bringing close to the needles, held in a partially raised position, a piece of equipment equipped with a plurality of annularly placed hooks. The hooks engage the tubular product along a circumference in such a way that, upon discharging the product from the needles, this is held on the hooks of the pick-up device. The latter is raised extracting from above the tubular product from the needle cylinder and so freeing the needle cylinder that can to be used for the formation of a new tubular knit product. The seam or looping of the toe is carried out by overturning a semi-arc of hooks on to the other and transferring the links from a semi-arc to the other pick-up device.
US-A-2001/0039816 describes a similar pick-up system of knit tubular products, which includes a rim of hooks brought next to the cylinder of needles from above to bring the product closer, that for this purpose is aspirated inside the pick-up device and, thanks to the aspiration, is kept engaged to the rim of hooks of the same device. This rim is then modified in its own arrangement bringing closer one to the other two flaps of the sewing point.
EP-A-679746 describes a pick-up system of knit tubular products in the circular machine that produces such tubular products by means of a couple of hooks that are approached, in a radially retreated position, to enter the cylinder space within the needles and, when the needle ring is reached whereon the tubular knit product is temporarily still engaged, one is moved away from the other, to engage in two opposed diametrical points the product which, discharged from the needles, can be extracted from the cylinder of needles to a couple of take elements.
WO-A-001869 describes a device, in which by means of a couple of hooks the tubular product is taken from the circular machine to a sewing machine where the product is engaged to the same hooks that have removed it from the needles of the circular machine. Hooks, oscillating to move one away from the other, distend the flaps of the toe to sew and insert them into the guillotine of the sewing machine.
U.S. Pat. No. 1,068,853 describes a pick-up device of a tubular knit product from a substantially equivalent circular machine to the device described in U.S. Pat. No. 7,107,797, equipped with a rim of subdivided hooks in two semi-arches. A semi-arc is overturned on to the other to transfer a semi-rank of stitches on an opposite semi-rank of stitches and therefore carry out the looping.